A new photochromic diarylethene compound, 1-[2-methyl-5-(3-chlorophenyl) -3-thienyl]-2-[2-methyl-5-(2-pyridine)-3-thienyl]perfluorocyclopentene(1a) was synthesized. its photochromism was investigated. It exhibited good photochromism and functioned as an effective fluorescent photoswitch both in solution and in PMMA films.